This invention relates to a stock solution of a release agent for green sand mold forming containing a hydrocarbon oil as the main component for lubrication and to a release agent for green sand mold forming.
A green sand mold which is the most based type of mold stays in the main stream of molds because its advantages are a good forming productivity, inexpensive materials for mold, and applicability for repeated use compared with other molds such as thermosetting mold, self-hardening mold, and gas-hardening mold.
The applicant of this invention provided a release agent for green sand mold forming which is an water-in-oil (W/O) emulsion, or a system of oil phase of hydrocarbon containing dispersed water phase, (refer to the Examined Japanese Patent Publication No. 63-29625).
This type of release agent has, however, the following disadvantages.
(1) Since the emulsion system used is the water-in-oil (W/O) type, the system can not diluted with water. Accordingly, the system needs to be prepared from the production stage to have a composition of application. This requirement causes problems with regard to shipment and storage. PA0 (2) The water content is limited to approximately 60% at the highest from the standpoint of stability of the prepared liquid and releasability of the product. This percentage of water content is not sufficiently high in terms of resource saving and safety against fire. PA0 (1) A preferable mode of the stock solution of a release agent for green sand mold forming of this invention is a stock solution of a release agent for green sand mold forming containing a hydrocarbon oil as the main component for lubrication, wherein the stock solution contains 1) a surface active agent as the dispersant and 2) an anionic surface active agent and/or strong basic amine as the wettability improving agent as essential components besides the hydrocarbon oil, and wherein the stock solution is used upon diluting it with water to prepare an oil-in-water emulsion. That type of composition achieves the first object of this invention and has the advantages and effect described below. PA0 (2) Another preferable mode of this invention is a stock solution of a release agent for green sand mold forming containing a strong basic amine and a higher fatty acid and/or ethylene glycol group as the essential components, wherein the stock solution is diluted with water to an adequate viscosity to use in the form of an aqueous solution. This type of composition achieves the second object of this invention and has the advantages and effect described below.
To cope with these concerns, the release agent may be prepared in the oil-in-water (O/W) emulsion. However, a uniform lubricant film is considered difficult to form on the surface of a mold after being used for forming. The reason of the difficulty is that, since the main component for lubrication is a hydrocarbon oil, the surface of a mold once used for forming by applying a releasing agent, particularly a metallic mold, leaves the oil component on the surface thereof, which remained oil repels a release agent of water-based O/W emulsion when it is applied onto the surface of the metallic mold.
An object of this invention is to provide a stock solution of release agent for green sand mold forming, which stock solution is applicable in a form of O/W emulsion and is diluted at the point of application.
Another object of this invention is to provide a stock solution of a release agent for green sand mold forming, which stock solution is applicable in a form of an aqueous solution and does not require the use of hydrocarbon oil.